An opaque structure appears how on a radiograph?

An opaque structure appears white on a radiograph because it absorbs more of the X-rays than surrounding tissues, which allows less radiation to reach the detector. This process occurs because denser materials, such as bone or metal, interact with X-rays in such a way that they prevent them from passing through. As a result, these areas appear white on the radiograph, contrasting sharply with less dense structures, which allow more X-rays to pass and thus appear darker. The understanding of radiographic density is crucial in interpreting images, as recognizing variations in opacity can help clinicians identify and diagnose various conditions based on the structures observed.